JP2005075856A - Rubber composition for tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rubber composition having low heat build-up properties compatible with rigidity (maneuvering stability). <P>SOLUTION: The rubber composition for tires comprises fine powder cellulose fibers in an amount of 2-100 pts. wt. based on 100 pts. wt. of a diene rubber. The fine powder cellulose fibers are prepared from natural vegetable fibers and have ≤100 μm average particle diameter. A silane coupling agent in an amount of 2-20 pts. wt. based on 100 pts. wt. of the fine powder cellulose fibers is preferably contained. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a rubber composition for tires, and particularly relates to a rubber composition for tires that can achieve both excellent low heat generation properties and rigidity (steering stability).

  Tires consist of various components, and rubber blends that meet the required performance required for each component are used.

  The rigidity of rubber has a great influence on the steering stability of the vehicle, and carbon black has been mainly used as a reinforcing agent for imparting rigidity to the rubber. However, the use of carbon black makes it easy for the rubber to generate heat.

  Further, due to the recent demand for lower fuel consumption of automobiles, lower heat generation is also required for rubber compounding in tires. A simple method for reducing the heat generation is to reduce the amount of carbon black as a reinforcing agent, but at the same time, the rigidity is lowered and the steering stability is deteriorated. Further, although heat generation can be suppressed by replacing carbon black with silica, it is difficult to maintain steering stability because of a decrease in rigidity.

  On the other hand, among the various components of the tire, the tread is exposed to friction with the road surface, and in addition to the above requirements, wear resistance is also required. For example, it has been reported that a rubber composition for a tire tread having excellent wear resistance can be provided by blending a powder processed product containing a cellulose substance such as rice husk (Patent Document 1). However, in the components other than the tread, the requirement for wear resistance is not so high, and it is necessary to achieve both low heat generation and rigidity (steering stability) superior to improving the wear resistance.

JP 2000-129038 A

  An object of the present invention is to provide a rubber composition capable of achieving both excellent low heat generation properties and rigidity (steering stability).

  The present invention relates to a rubber composition for tires containing 2 to 100 parts by weight of finely powdered cellulose fibers with respect to 100 parts by weight of diene rubber, wherein the finely powdered cellulose fibers are prepared from natural plant fibers and have an average particle size The present invention relates to a tire rubber composition having a diameter of 100 μm or less.

  Moreover, it is preferable to contain 2-20 weight part of silane coupling agents with respect to 100 weight part of said fine powder cellulose fibers.

  According to the present invention, a tire capable of achieving both low heat buildup and rigidity (steering stability) by blending finely powdered cellulose fibers prepared from natural plant fibers into a rubber component and using them in components other than treads. Can be provided.

  The tire rubber composition used in the present invention comprises a diene rubber and finely divided cellulose fibers.

  Examples of the diene rubber used in the present invention include natural rubber (NR), styrene-butadiene rubber (SBR), butadiene rubber (BR), and the like, and they can be used alone or as an arbitrary blend.

  The finely powdered cellulose fibers used in the present invention are prepared from natural plant fibers. Examples of natural plant fibers include wood, rice hulls, wheat husks, cork pieces, and sawdust.

  Finely powdered cellulose fibers can be obtained by chemically treating natural plant fibers with chemicals such as sodium hydroxide or ozone. The finely powdered cellulose fibers obtained by the preparation have very little lignin substance that binds cellulose fibers compared to natural plant fibers, and therefore the fibers are finer than untreated products. Further, many OH groups on the surface of the cellulose fiber are exposed, which is excellent in that the reactivity with the coupling agent or the like is high.

  The fine powder cellulose fiber has an average particle size of 100 μm or less, preferably 50 μm or less. When the average particle diameter exceeds 100 μm, dispersion in rubber becomes difficult.

  The compounding amount of the finely powdered cellulose fiber is 2 to 100 parts by weight, preferably 5 to 50 parts by weight, more preferably 10 to 30 parts by weight with respect to 100 parts by weight of the rubber component. If the amount is less than 2 parts by weight, a sufficient effect cannot be obtained. Moreover, when it exceeds 100 weight part, dispersion | distribution of a fine powder cellulose fiber will become difficult.

  The fine powder cellulose fiber can improve the reinforcement by using it together with a silane coupling agent in the same manner as silica. It can be inferred that this is due to the reaction with the OH group on the surface as in the case of silica.

  Specific examples of the silane coupling agent include bis (3-triethoxysilylpropyl) tetrasulfide, bis (2-triethoxysilylethyl) tetrasulfide, bis (3-trimethoxysilylpropyl) tetrasulfide, and bis (2 -Trimethoxysilylethyl) tetrasulfide, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 2-mercaptoethyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, 3-nitropropyltrimethoxysilane, 3 Nitropropyltriethoxysilane, 3-chloropropyltrimethoxysilane, 3-chloropropyltriethoxysilane, 2-chloroethyltrimethoxysilane, 2-chloroethyltriethoxysilane, 3-trimethoxysilane Rupropyl-N, N-dimethylthiocarbamoyl tetrasulfide, 3-triethoxysilylpropyl-N, N-dimethylthiocarbamoyl tetrasulfide, 2-triethoxysilylethyl-N, N-dimethylthiocarbamoyl tetrasulfide, 3-trimethoxy Examples thereof include silylpropyl benzothiazole tetrasulfide, 3-triethoxysilylpropyl benzothiazole tetrasulfide, 3-triethoxysilylpropyl methacrylate monosulfide, and 3-trimethoxysilylpropyl methacrylate monosulfide. These may be used alone or in combination of two or more. In the silane coupling agent, bis (3-triethoxysilylpropyl) tetrasulfide and the like are preferable from the viewpoint of achieving both the effect of adding the coupling agent and the cost.

  The blending amount of the silane coupling agent is preferably 2 to 20 parts by weight and more preferably 8 to 12 parts by weight with respect to 100 parts by weight of finely powdered cellulose fibers. If the silane coupling agent is less than 2 parts by weight, the blending effect tends to decrease. On the other hand, when the amount exceeds 20 parts by weight, no significant performance improvement is recognized, and the cost increases.

  Carbon rubber can be blended as a reinforcing agent in the tire rubber composition used in the present invention.

  The compounding amount of carbon black is preferably 2 to 100 parts by weight, more preferably 10 to 60 parts by weight with respect to 100 parts by weight of the diene rubber component. When the blending amount is less than 2 parts by weight, there is a tendency that excellent handling stability cannot be obtained. Moreover, when it exceeds 100 weight part, there exists a tendency for rolling resistance to increase.

  In addition to the above-mentioned additives, the rubber composition of the present invention further includes various additives usually used in the rubber industry, for example, reinforcing agents such as silica, softeners such as aromatic oils, anti-aging agents, and waxes. Further, a vulcanizing agent, a vulcanizing aid, a vulcanization accelerator and the like can be blended.

  A tire can be produced by a usual method using the rubber composition of the present invention. That is, if necessary, the rubber composition of the present invention blended with the above-mentioned chemicals is extruded in accordance with the shape of each member of the tire at an unvulcanized stage and molded by a normal method on a tire molding machine. Thus, an unvulcanized tire is formed. The unvulcanized tire is heated and pressed in a vulcanizer to produce a tire.

  Specific examples and comparative examples of the present invention are shown below, but the present invention is not limited to the following examples.

The raw materials used in the examples and comparative examples are summarized below.
NR: RSS # 3
BR: Nipol BR1220 manufactured by Nippon Zeon Co., Ltd.
Carbon black HAF: Seast NH manufactured by Tokai Carbon Co., Ltd.
Fine powder cellulose fiber: KC Flock (average particle size 40 μm) manufactured by Nippon Paper Chemicals Co., Ltd.
Silane coupling agent: Si69 (bis (3-triethoxysilylpropyl) tetrasulfide) manufactured by Degussa
Zinc oxide: Zinc oxide stearic acid manufactured by Mitsui Mining & Smelting Co., Ltd.
Aromatic oil: Diana Process AH-24 manufactured by Idemitsu Kosan Co., Ltd.
Anti-aging agent: Antigen 6C (N- (1,3-dimethylbutyl) -N′-phenyl-p-phenylenediamine) manufactured by Sumitomo Chemical Co., Ltd.
Wax: Sunnock N manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.
Sulfur: Powder sulfur vulcanization accelerator manufactured by Karuizawa Sulfur Co., Ltd .: Noxeller CZ (N-cyclohexyl-2-benzothiazylsulfenamide) manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.

Examples 1-4 and Comparative Examples 1-3
In accordance with the blending contents shown in Table 1, the blending components excluding sulfur and the vulcanization accelerator are kneaded for 3 minutes using a Banbury mixer, and the powder sulfur and vulcanization accelerator as the vulcanizing agent are then mixed with a roll. A rubber composition was obtained by blending.

  A test tire (size: 195 / 65R15) using the obtained rubber composition for the base tread portion was produced and subjected to the following tests. The results of each test are shown in Table 1.

(Cellulose dispersion)
The rubber after kneading was visually observed to confirm the presence or absence of agglomerates of finely divided cellulose fibers.
◯: Indicates that no agglomerates of cellulose fibers are observed.
X: It shows that the aggregate of a white undispersed cellulose fiber is seen visually.

(Rolling performance)
Using a rolling resistance tester, the rolling resistance when the sample tire was run at a rim of 15 × 6JJ, an internal pressure of 230 kPa, a load of 3.43 kN, and a speed of 80 km / h was measured. displayed. A larger index is better.

(Maneuvering stability)
The test tires were mounted on all the wheels of a vehicle (domestic FF2000cc) and the vehicle was run on the test course, and the running stability was evaluated by sensory evaluation of the driver. Evaluation was made relative with 10 points being the perfect score and Comparative Example 1 being 6 points. The larger the evaluation, the better.

  From the evaluation results of Examples 1 to 3, it can be seen that the rubber composition containing finely powdered cellulose fibers in the range of 2 to 100 parts by weight has reduced rolling resistance and is excellent in handling stability.

  Moreover, it turns out that rolling resistance can further be reduced from the evaluation result of Example 4 by using a silane coupling agent together.

Claims (2)

A rubber composition for tires containing 2 to 100 parts by weight of finely powdered cellulose fibers with respect to 100 parts by weight of diene rubber, wherein the finely powdered cellulose fibers are prepared from natural plant fibers and have an average particle size of 100 μm or less A tire rubber composition. The rubber composition for a tire according to claim 1, comprising 2 to 20 parts by weight of a silane coupling agent with respect to 100 parts by weight of the finely powdered cellulose fibers.